Mechanism of Aryldestannylation of Alkenylstannanes with Arylpalladium Complexes

Arpd(PPh_3)_2I和Arpd(PPh_3)_2BF_4芳基去单宁化PhCH=CHSnR_3和Ph(R_3SN)C=CH_2(R=Bu，Ph)分别得到PhCH=Char和Ph(Ar)C=CH_2。然而，在没有强中性配体如PPh@3的情况下，Palladum络合物的反阴离子对反应曲线有很大的影响。与PhCH=CHSnR_3，[Arpd]^+BF_4^-反应得到Ph(Ar)C=CH_2，而Ar-Pd-I得到PhCH=CH。在PPh_3或I^-等配位强配体存在下，芳基钯配合物以跨金属还原消除机理生成芳基去脂基锡烷。在没有配位强配体的情况下，与[Ar-Pd]^+BF_4^-的反应按以下方案进行。在钯催化的有机亲电体与有机金属的C-C偶联反应中，器官-钯物种有望成为关键的中间体。目前的结果说明了有机钯中间体的配体在设计反应途径中的重要作用。

Both ArPd(PPh_3)_2I and ArPd(PPh_3)_2BF_4 aryldestannylated PhCH=CHSnR_3 and Ph(R_3Sn)C=CH_2(R=Bu, Ph)to give PhCH=CHAr and Ph(Ar)C=CH_2, respectively. In the absence of strong neutral ligands such as PPh@_3, however, the counter anion of the palladum complexes showed drastic effect on the reaction profile. Reaction with PhCH=CHSnR_3, [ArPd]^+BF_4^- gave Ph(Ar)C=CH_2, whereas Ar-Pd-I gave PhCH=CHAr.In the presence of coordinatively strong ligands such as PPh_3 or I^-, arylpalladium complexes aryldestannylate alkenylstannanes via transmetallation-reductive elimination mechanism as following scheme.<<chemical formula>>In the absence of coordinatively strong ligands, the reaction with [Ar-Pd]^+BF_4^- proceeds through addition-elimination mechanism as following scheme.<<chemical formula>>In the palladium catalyzed C-C coupling of organic electrophiles with organometallics, organs-palladium species expect to be a key intermediate. Present results exemplify an important role of the ligands of organopalladium intermediates to design reaction pathway.